(1) Field of the Invention
The present invention relates generally to a submarine shutterway and more particularly to a submarine torpedo tube shutterway that adapts to both the torpedo swimout and ejection launch modes.
(2) Description of the Prior Art
Existing submarine launch systems have torpedo tubes which are arranged so that their centerlines are canted away from the centerline of the ship at an angle of 10.degree. or less. The torpedo tubes themselves are cylinders having a flat end to accommodate a pressure containing muzzle door. Behind the muzzle door a fired torpedo is guided until it exits the outer hull of the submarine. As a result of the intersecting angle of the torpedo tube and the circularity of the hull itself, the outer door or shutterway is normally quite long in a horizontal direction.
The newest classes of Navy submarines will have torpedo launch tube systems that will be different from existing launch systems in a number of ways. First, the torpedo tubes will be installed with their centerlines parallel to the submarine's centerline in order to allow the launch system to achieve a 0.degree. firing angle with respect to the forward velocity of the submarine. This reduces the number of force vectors acting on the torpedo as it is launched. Secondly, the torpedo tube and its shutterway must be capable of handling two different types of torpedo launches, namely, an ejection launch and a swimout launch.
An ejection launch is one that uses water propulsion to push the torpedo out of the torpedo tube. In such a launch, the torpedo's propellers are not activated until a torpedo clears the hull of the submarine. The water propulsion, or ejection plume as it is known, is applied to the aft end of the torpedo and must be strong enough to push the torpedo through the strong flow field that exists along the boundary layer between the submarine hull and the sea water. Accordingly, in order to support the ejection launch, the torpedo tube and torpedo tube shutterway must only allow the torpedo to pass through while constraining the ejection plume.
A swimout launch is one that uses the propulsion generated by the torpedo's propellers within the torpedo tube. This type of launch is quieter than the aforementioned ejection launch. However, it is also less stable since the velocity generated by a swimout launch is less than the velocity generated by the ejection launch. Thus, the choice of a swimout versus an ejection launch is based upon several factors such as the speed of the submarine and noise considerations. In order for a swimout launch to occur, water must be allowed to flow around the forward end of the torpedo, along its body and into the torpedo's propellers. Accordingly, in order to support a swimout launch, the torpedo tube and torpedo tube shutterway must be large enough to allow the torpedo to pass through and provide a flow area around the torpedo for water to flow into the torpedo's propellers.